Peroxygen bleaching compounds are useful for bleaching fabrics, textiles and other materials, but are less effective than could be desired when bleaching temperatures less than 70.degree. C. are utilized. Thus, peroxygen bleaching compositions desirably include activators, particularly for monopersulfate and monoperphosphate systems generating hypochlorite, in order to provide effective concentration of the bleaching agent under cooler wash temperature conditions.
In a technical service report dated Feb. 1, 1970 by American Potash & Chemical Corporation, it was reported that certain ketones (i.e. acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone), activate persulfate bleaches in the presence of an alkaline buffer providing a pH of at least 8. U.S. Pat. No. 3,822,114, inventor Montgomery, issued July 2, 1974 discloses pyroxygen bleaching compositions which include a peroxygen bleaching compound, such as water-soluble monopersulfates and monoperoxy phosphates, and an aldehyde or ketone activator compound for the peroxygen compound. The aldehydes or ketones disclosed are said to activate the peroxygen compounds in aqueous solution having a pH of about 7 to about 12, and a preferred embodiment includes the optional addition of a water-soluble chloride salt to yield hypochlorite type bleaching.
Dry bleaching compositions, particularly useful for low temperature applications, are described in U.S. patent application Ser. No. 629,695, filed July 11, 1984, entitled "CONTROLLED GENERATION HYPOCHLORITE COMPOSITIONS AND METHOD," inventors Casella, et al., of common assignment herewith, in which generation of hypochlorite by reaction between a peroxygen bleaching agent and a chloride salt is promoted by an activator, preferably an aromatic diol in ester form having the structure illustrated below: ##STR3## wherein one of R.sub.1 and R.sub.2 is an alkyl group having at least one to about eight carbon atoms, the other is hydrogen or an alkyl group having at least one to about eight carbon atoms, and R.sub.3, if present, may be a substituent such as sulfonate, carboxylate, alkyl ethoxylate, quarternary ammonium or lower alkyl (e.g., methyl, ethyl or butyl).
As noted by D. Johnston, Chemistry & Industry 24, 1000 (1982), attempts to mono-derivatize benzene diols usually lead to a mixture of the unreacted difunctional compounds, the mono-substituted product and the bis-derivatized by-product. Johnston describes a procedure giving good yields of hydroquinone monoacetate from hydroquinone by reacting the hydroquinone with acetic anhydride in an equimolar ratio.
However, attempts to adapt the Johnston method to resorcinol by reaction with longer chain acid anhydrides have been found to produce disappointing yields of monoester and have favored formation of symmetrical diesters.